Hypersomnia can refer to extreme excessive sleepiness or excessive sleeping. Hyper means 'too much' and somnia refers to issues relating to sleep. Sufferers of hypersomnia find it difficult to stay awake throughout the day. This sometimes results in falling asleep in inappropriate places at inappropriate times (such as at school or work). Hypersomia is fairly common - research suggests that 40% of individuals have hypersomnia sometimes. It is only if this is a chronic condition that is needs to be checked out.
Causes of hypersomnia include narcolepsy, sleep apnea, sleep deprivation, drugs or alcohol, brain injury or disorders, and depression.
An example of a hypersomniac would be a person who has sleep apnea and although they sleep over 8 hours a night feel exhausted all day long and constantly fall aleep while at work.